Abrading apparatus



March 14, 1944. c. TURNBULL ABRADING APPARATUS Filed Dec. 31, 1941 5 Sheets-Sheet 1 INVENTOR. ja Md 6 flank/ll fl TTOPNE Y March 14,1944. QTURNBULL 2,344,475

ABRADING APPARATUS Filed Dec. 31, 1941 5 Sheets-Sheet 2 INVENTOR.

D. C. TURNBULL ABRADING APPARATUS March 14, 1944.

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INVENTOR. 72011544 fl/Znf %z. m

/l TTOIPNEY March 14, 1944. c TURNBULL ABRADING APPARATUS Filed Dec. 51, 1941 5 SheetsSheet 4 Patented Mar. 14, 1944 ABRADING APPARATUS David C. Turnbull, Mishawalra, Ind., assignor to The American Foundry Equipment Company, Mishawaka, Ind., a corporation of Delaware Application December 31, 1941, Serial No. 425,082

19 Claims. ('01. 51-9) This invention relates to abrading apparatus, and more particularly to blast cleaning apparatus whereby relatively large and irregularly shaped castings and metal objects may be subjected to the cleaning or treating action of any desired number of centrifugally projected abrasive streams.

In the blast cleaning and treating of numerous relatively large and cumbersome or irregularly shaped metal objects the problem is presented of conveying and manipulating the metal objects in successive centrifugally projected abrasive streams so as to thoroughly clean to the desired degree all irregular projections and cavities which the surfaces of the objects present. To effect this result the objects should be advanced into each of the successive blasting streams with the least possible delay and yet be permitted to dwell in each of the blast streams for a carefully controlled period.

Abrasive blasting wheels having means associated therewith for accurately controlling the direction of fire of the abrasive blast, as illustrated and described in Peik Pat. No. 1,953,566, are highly effective in the blast cleaning and treating of numerous metal objects. Since such abrasive throwing wheels, each throwing many hundreds of pounds of abrasive per minute, are relatively heavy and must be rotated at very high speeds, it is generally most convenient to maintain the wheels in a relatively stationary position and manipulate the workpieces in each of the blast streams. This requires that all the projections and cavities on the surfaces of the workpieces to be cleaned must be manipulated in the fan-shaped stream projected from each wheel, and further requires that the surface areas to be cleaned reside in the blasting streams for a controlled period of time so that all surfaces will be thoroughly and adequately cleaned and yet not over-abraded or damaged by the blasting stream, which may quickly result from relatively short over-exposure due to the large volume and terrific speed of the abrasive projected by abrasive throwing wheels of the type above-referred to.

An object of this invention is to provide improved blasting apparatus having means associated therewith for accurately controlling the period of exposure of the workpieces in centrifugally projected abrasive streams.

Another object of this invention is to provide improved mechanism for ass u'ing positive and accurate indexing of the advancing workpieces in one or more abrasive blasting streams so that the maximum quantity of projected abrasive will be employed in doing useful work.

Another object of this invention is to provide improved mechanism for rotating the workpieces at controlled speed in one or more centrifugally projected abrasive streams.

A further object of this invention is to provide improved blasting apparatus which is substantially automatic, smooth and eflicient, foolproof in operation, sturdy and lasting in construction, simple and relatively inexpensive in design, and which achieves high speed production output at relatively lower costs than apparatus of this type heretofore provided.

Other objects of this invention will become apparent as the disclosure proceeds.

Various other features and advantages of the invention will be apparent from the following particular description and from an inspection of the accompanying drawings.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Fig. 1 is a top plan view of the apparatus;

Fig. 2 is a front elevational view of the apparatus shown in Fig. 1;

Fig. 3 is an end elevational view of the apparatus, certain parts being broken away to illustrate structural details;

Fig. 4 is an enlarged fragmentary elevational view of the work-supporting hangers and spinner mechanism as the same appears when one looks along line 4-4 of Fig. 1;

Fig. 5 is an enlarged vertical cross-sectional view through one of the intermediate work-supporting hangers and adjacent spinner chain guiding or supporting devices, as the same appears when looking along line 5-5 of Fig. 4;

Fig. 6 is an enlarged vertical cross-sectional view through one of the alternate work-supporting hangers and adjacent spinner chain supporting device, as the same appears when viewed along line 66 of Fig. 4;

Fig. '7 is a fragmentary vertical cross-sectional view showing the driving parts of the inter mediate work-supporting hanger as the same appears when viewed along line 1-1 of Fig. 5; and

Fig. 8 is a diagrammatic illustration of the wiring diagram and electric control mechanism for regulating the advance movement of the work-supporting hangers through the blasting streams.

Similar reference characters refer to similar parts throughout the several views of the drawings and the specification.

Referring to the drawings, the blastin apparatus comprises generally a blast cabinet A into which the workpieces p are conveyed by alternate and intermediate workpiece suspension hangers B and B which are adapted to roll along a circuitous track C. The surfaces of the workpieces p are blasted with abrasive during their residence in the cabinet A by means of a plurality of centrifugal throwing wheels W which operate to project controlled streams of abrasive a and a against the workpieces. The workpiece-supporting hangers B and B are advanced into the blasting zone by means of hanger-advancing mechanism D which operates to advance the workpieces into each of the successive blasting streams where they are permitted to dwell for a predetermined time period before they are advanced out of the blasting streams. Mechanism E is also provided for rotating the workpiece-supporting hangers during their residence in the blasting streams, so that all surfaces, including projections and cavities in the workpieces, are fully blasted and cleaned to the desired degree.

As shown more particularly in Figs. 1, 2 and 3, the blast cabinet A comprises generally an entrance vestibule section I, a blasting zone section 2, and an exit vestibule section 3. The entrance and exit vestibule sections provide hallwaysthrough which the work-supporting hangers move in entering and leaving the main blasting section 2 disposed therebetween. Each of the vestibule sections l and 3 is defined by an outer side wall 4, an inner side wall 5 and a front entrance wall 6. The main blasting section is defined by spaced side walls 1, a rear wall 8 and a front wall 9. The entire top of the cabinet is enclosed by a top wall III, which extends over the entrance vestibule l, main blasting section 2, and exit vestibule 3. The walls of the cabinet are held together in rigid assembly by suitable framework IS. The entrance vestibule section I and the exit vestibule section 3 may rest upon a sturdy raised base or table II, while the main blasting section 2 may rest directly upon the building floor F.

An abrasive-receiving hopper l2, as illustrated more particularly in Figs. 2 and 3, may be provided to form the bottom wall of the blasting section 2 of the cabinet. If the distance between the front wall 9 and the rear wall 8 of the blasting section of the cabinet is made of substantial depth as indicated, it may be desirable to provide a second abrasive-receiving hopper l3 which sets into a pit F in the floor to receive the abrasive from the funnel H of the hopper l2. Abrasive-elevating and screening mechanism G may be provided for cleaning and cycling the abrasive from the hopper l3 to the abrasive throwing wheels W.

The conveyor track C is positioned above the top wall ll! of the cabinet and may be of any desired shape most convenient for plant operations to carry the workpieces p to the blasting cabinet, through the blast cabinet, and away from the blast cabinet to an unloading zone. The conveyor track C, as illustrated in Figs. 1, 2 and 3, is shown as comprising a closed circuitous track having the loading section 0' thereof positioned outside of the cabinet, a section C" which extends over the top wall I0 of the cabinet, and an unloading section 0" extending beyond the top wall area of the blast cabinet. The conveyor track C may be formed as an I-beam section having a bottom flange l6 along which the work-supporting carriers B and B are adapted to roll. The track C is braced and supported by suitable framing I5 suitably secured to the cabinet framework l5 orto the ceiling of the plant, as found most convenient.

In order that all surfaces of the workpieces p be fully cleaned to the desired extent during residence of the workpieces in the abrasive streams a and a, it is desirable to rotate the workpieces p in each blasting stream for a predetermined period. The workpieces 1) should also obviously be arranged as close together as possible in order that the abrasive streams may be utilized to the maximum in cleaning the workpieces and not be projected between the spaced workpieces without cleaning the surfaces thereof. It is also obvious that where the workpieces p have projections p of substantial length and cavities p" of substantial depth, the workpieces can be suspended closer together if alternate workpieces are rotated in opposite directions. While it is an old expedient to rotate the workpieces in opposite directions in the blasting zone so that the blasting streams may be utilized to their maximum usefulness, I have provided improved mechanism for rotating the workpieces in the blasting streams with alternate workpieces rotating in the same direction and intermediate workpieces rotating in the opposite direction, which is simple in design, sturdy and lasting in construction, and positive in operation.

This desirable objective is achieved by so constructing the alternate work-supporting hangers B and the intermediate work-supporting hangers B' that the workpieces on all the alternate hangers may be rotated in one direction and the workpieces on all the intermediate hangers may be rotated in the opposite direction by a single drive chain. While the alternate hangers B and the intermediate hangers B have been illustrated in Figs. 1, 2, 3 and 4 as being some distance apart, this has been done for the sake of clearness as it will be understood that the hangers can be positioned as close together as the shape and size of the workpieces p to be cleaned will permit.

Both the alternate and intermediate worksupporting carriers B and B, as illustrated more particularly in Figs. 4, 5 and 6, comprise a pair of rollers I! which roll on the flange l6 of the I- beam shaped track C. The rollers I! are secured to the arms IQ of the U-shaped yoke it, each arm carrying a stub shaft 20 on which the rollers H are journaled. Each yoke I8 is provided with a downwardly extending leg 2| which terminates in a cup-shaped receiver 22. A tubular sleeve 23 has the upper end thereof projecting into the cup 22 and is firmly secured to the cylindrical wall of the cup. A spindle 24 is rotatably mounted within the sleeve 23 by a thrust bearing comprising bearing part 25 fixed to the upper end of the sleeve 23 and bearing part 26 fixed to the upper end of the spindle 24, the bearing parts 25 and 26 having a raceway therebetween for ball bearings 21. The spindle 24 may be provided with a flattened head 28 which rests on the bearing part 25.

Both the alternate and intermediate hangers B and B are each provided with a work-supporting spindle 33 which is connected to the carriage spindle 24. The spindles 33 are of willcient length to extend through a slot 35 in the top wall In of the cabinet, the slot 35 being directly below cabinet section C" of the track C. The lower end of each hanger spindle 33 is provided with a hook element 33- to which the workpiece 10 may be conveniently attached.

' sleeve 23.

Each of the work-supporting spindles 33 and the workpiece which 'itsupports may be freely rotated from the thrust bearing contained within the stationary sleeve 23 of the hanger carriage.

As shown more particularly in Figs. 4 and 6, the spindle 33 of eachalternate hanger extends into a socket 32 which is formed in the lower end of a heavy collar member 29. The upper end of the work-supporting spindle 33 is removably secured within the socket 32 by means of a suitable key 34. The heavy collar member 29 is provided with a bearing collar 39 secured to the upper end thereof which is positioned adjacent a bearing collar 3| secured to the lower end of the sleeve 23, thus permitting the heavy collar member 29 to freely rotate within the Each alternate work-supporting spindle has fixed thereto a sprocket 36 designed to mesh with a continuous spinner chain-31 described in more detail hereinafter.

The work-supporting spindle 33 of each intermediate hanger B. is also provided with a sprocket 36' of the same diameter as the alternate sprockets 36, and is designed to be driven by the same spinner chain 31 which drives the spinner sprockets 36 of the alternate hangers. The spinner sprocket 36' associated with the intermediate hangers B is, however, connected to its carrier spindle 24 in such a manner that its work-supporting spindle 33'ls rotated in a direction opposite to. the direction of rotation of the work-supporting spindles 33 associated with'the alternate hangers.

As illustrated more particularly in Figs. 4, 5

and '1, each intermediate hanger is provided with a heavy collar member 29' which is'fixedly secured to its sleeve 23. The lower end of each collar 29' is provided with a laterally extending flange 38 which is secured as by removable bolts of each intermediate work-supporting spindle 33. The bevel gear 45 and work-supporting spindle 33 are secured to the end 24' of intermediate hanger spindle 24 by a key or pin 41 which extends through the hub portion 46, spindle 33 and end portion 24 of spindle 24.

Bevel gear 45 meshes with a bevel transfer gear 48 which'is supported upon the shank portion of a bolt 49 fixed to a plate 50 removably secured to the top wall 39 and bottom wall 5| of gear box 40 by means of removable screw bolts 52. To permit the bevel transfer gear 48 to rotate on the shank of its supporting bolt 49 without friction, a suitable ball bearing assembly 53 may be provided between the hub of the bevel gear 48 and its supporting bolt 49.

The bevel transfer gear 48 meshes with a bevel driving gear 54 secured to the upper end of a driving sleeve 55 which surrounds the work-supporting spindle 33. I the work-supporting spindle 33 substantially without friction by the provision of an upper roller bearing 56 and a lower roller bearing 51 positioned between the sleeve 55 and the work-supporting spindle 33. The gear sleeve 55 is prevent- The sleeve 55 rotates about 36', as by a set screw.

ed from sliding upwardly on the work-supporting spindle 33 by a collar 53 which is fixed to the spindle .33 as by pin 59 and which abuts the upper end .01 the sleeve 55. The lower end of the sleeve 55 projects through the bottom wall 5| of the gear box 49 and has secured to its outer periphery a heavy disc member 50. The driving sprocket 36' is firmly secured to the heavy disc 66 by spaced bolts 6|. The sprocket 36' is provided with a large circular opening 62 through which the work-supporting spindle 33 projects. A thrust bearing cup 63 is secured to work-supporting spindle 33 at a point below the sprocket A thrust bearing 65 is positioned within the cup 63 and provides a support for the driving sleeve 55.

The gear box may be packed with grease which may be prevented from dripping out through the aperture 66 in the bottom wall 5| of gear box 40 through which the driving sleeve 55 extends, by'a suitable sealing gasket which may comprise a gasket cup 61 fixed to the driving sleeve 55 and within which suitable packing material 68 may be placed. A sealing ring 69 secured to the bottom wall 5| of gear box 40 provides a further seal between the bottom wall 5 and the gasket cup 61.

The spinner sprocket 36' driven by spinner chain 31 rotates the driving sleeve 55 to which the driving bevel gear 54 is attached. Driving bevel gear 54 rotates bevel transfer gear 43 which has a driving connection with the gear attached to the upper end of the work-supporting spindle 33 of the intermediate hanger. In this arrangement it will be appreciated that bevel gear 45 attached to the spindle 33 is rotated in a direct on opposite to th driving bevel gear 54 attached to the driving sleeve so that the intermediate work-supporting spindle 33 will rotate in a direction opposite to its associated spinner sprocket 36'. All moving parts are maintained in well greased driving condition since all driving parts are lubricated fromthe grease that may be packed in gear box 40. By means of the driving device above described, the work-supporting spindle 33 of each intermediate hanger B' may be rotated in a direction opposite to the rotation of the work-supporting spindles 33 associated with the alternate hangers B, even though the spinner sprocket 36 associated with each intermediate hanger is rotated in the same direction as the spinner sprocket 36 associated with each alternate hanger by the same spinner chain 31.

All the hangers B and B are connected toether by means of a continuous conveyor chain 19 which is positioned directly beneath the track C. The conveyor chain 10 may be in the form of a heavy link chain comprising paired links 1| pivotally connected to intermediate links by heavy studs 13 which extend through aligned openings therein. The leg portion 2| of each hanger bracket 18 is provided with a reduced neck port on 14 which extends through aligned apertures in the paired links 1| and 12 so that the reduced neck portion 14 is substituted for the stud 13 at that point. The ends of adjacent paired links H seat between an enlarged collar portion 15 and an enlarged head portion 16 provided on each lee. 2|. Thus connected, the work-supporting angers B and B can be arranged in uniform spaced relationship with the rol ers |1 thereof free to roll on theflanges l6 of the track C.

The work-supporting hangers B are caused to travel along the track C by driving mechanism D which engages the conveyor chain 10, and comprises a conveyor driving motor I mounted oh the top wall I0 of the cabinet supplied with power from the primary power lines IOI and I02 so that the motor I00 operates continuously. A pulley wheel I03 is fixed to the motor shaft and carries a drive belt I04 trained around pulley I05 which normally idles on shaft I06 of reduction gearing housed within gear box TI. The reduction gearing in gear box II drives shaft I8 which carries a gear wheel 18. Gear wheel I8 meshes with a larger gear wheel 80 fixed to stub shaft 8|. Stub shaft 8I carries a large sprocket wheel 82 which meshes with the conveyor chain I0. The hangeradvancing mechanism D has also incorporated therewith devices for periodically advancing and indexing the workpieces in the abrasive streams a and a projected from the abrasive throwing wheels W. -These indexing devices will be more particularly described hereinafter.

Any desired number of abrasive throwing wheels W may be provided as may be necessary or desirable to eil'ectively clean the surfaces of the workpieces p under treatment at the desired production speeds. While I have illustrated two such abrasive throwing wheels in Figs. 1, 2 and 3, it will be appreciated that this invention is in no wise limited to the use of only two abrasive throwing wheels but any desired number thereof may be provided. The abrasive throwing wheels preferably used are control cage and impeller type wheels, such as disclosed in Peik Pat. No. 1,953,566 having certaitn refinements in design as illustrated in Unger Pat. No. 2,162,139. Each wheel W comprises generally a pair of side wall forming discs 83 and 84 having channel-shaped abrasive throwing blades85 mounted therebetween which extend inwardly short of the axis of rotation of the wheel to provide a central space. A tubular control cage 86 extends into the central space of the wheel and is normally stationary during operation of the wheel but is so mounted that it may be adjusted to place the discharge outlet in the cage in any desired clock-dial position to regulate the direction of fire of the abrasive stream projected therefrom. The wheel is equipped with a vaned impeller 81 positioned within the control cage 86 and fixed to the rear side wall disc 84 of the wheel to rotate with the blades 85 thereof. Abrasive is supplied to the interior of the impeller by means of a feed spout 81 having a funnel formation 88 at the upper end thereof.

Each wheel W may be positioned entirely within the blasting section 2 of the cabinet and has a hub 88 secured to the rear side wall disc 84 thereof. The wheel shaft 90 fixed to the hub 89 is preferably positioned on the outside of the cabinet and is rotatably mounted in suitable spaced bearings 9| which may be secured to the front wall of the cabinet. The wheel shaft 80 is driven by a motor 82 having a drive pulley 93 over which V-belts 94 are trained, the V-belts 84 also being trained around the pulley 95 secured to the end of the wheel shaft 90.

The front wall 9 of the cabinet may be recessed in the manner illustrated in Fig. 1 so as to provide an offset from wall portion 9' upon which the motor 82 and bearings 8| are mounted, and a side wall portion 9" having an opening therein through which a portion of the hub 89 of the wheel projects. In this arrangement the driving motor 92, V-belts 94, wheel shafting 90 and shaft bearings 9| are fully protected from flying abrasive, while the abrasive throwing wheels W are free to operate within the blasting section 2 of the cabinet. It will be noted, by referring more particularly to Figs. 1 and 3, that the rear wall 8 of the blasting section 2 of the cabinet I is spaced a substantial distance rearwardly of the blasting position of the workpieces p moving along the section C" of the track C. In this construction of the cabinet the side walls I and rear wall 8 of the blasting section 2 of the cabinet are spaced so far away from the workpieces that any abrasive which may fail to strike the workpieces p advancing through the blasting zone has lost much of its abrading force before it con tacts the cabinet walls.

It will be noted by referring more particularly to Figs. 2 and 3, that the wheels W may be arranged at difierent elevations and may be rotated in opposite directions so as to project their fan-shaped streams a and a in a manner to most effectively and thoroughly clean all surface areas of the workpieces p operated upon. The workpieces p are moved into the successive blast streams a and a, dwell therein for a predetermined period, and then successively advanced out of the blast streams by indexing devices associated with the hanger-advancing mechanism B.

The indexing devices asociated with the hanger-advancing mechanism D operate to halt the work-supporting hangers B and B' in the blasting zone for a predetermined period of time and thereafter to automatically advance the work-supporting hangers B and B' into the next treating zone for a predetermined dwell, without halting .the driving motor I 00 which advances the hangers. Thus the loss of power and emciency resulting from halting the driving motor is obviated and exact indexing of the workpieces in the blasting zone is effected.

The mechanism for advancing and indexing the workpieces p in the blasting zone is, illustrated more particularly in Figs. 1 and 8. The conveyor-driving motor I00 drives motor belt I 04 trained around pulley I05 which normally idles on shaft I06 of reduction gearing housed in gear box 11 and when idling does not rotate the conveyor chain. sprocket wheel 82. The idler pulley I05, however, has a clutch I08 attached thereto which also idles on shaft I06. A companion clutch I01 is fixed to rotate with the shaft I06 but is free to slide thereon, as shown in Fig. 8. The companion clutch I0'I has a groove I09 therein which receives aroller fixed to the end of a rocking lever IIO which is pivoted on pivot III. The other end of rocking lever I I0 is connected to the end of a solenoid shaft II2, so that when the solenoid H3 is energized the companion clutch I01 is held out of engagement with the clutch I08 so that the conveyor chain sprocket 82 does not rotate. When the solenoid H3 is de-energized, a coil spring I I5 which surrounds the solenoid shaft II2 presses against a collar Ill on solenoid shaft II2 to pivot rocking lever IIO, so as to move the companion clutch I01 into driving engagement with the clutch I08 thus causing the motor I00 to drive main conveyor chain sprocket 82.

The solenoid II3 has one end of its coil connected to a secondary circuit IIII' attached to the primary motor circuit I02. The other end of the solenoid coil is connected to lead wire 5' which is connected to contact point I21 arranged to contact a movable switch block I25. Movable switch block I25 is arranged to contact terminal I26 of lead wire I28 which is connected by wire I28 to a time clock I80.

The movable switch block I25 is fixed to the end of a shaft I2I which is provided with a pair of legs I22 for supporting a contact roller I20. The block shaft I2I extends through astationary collar I23 against which a coil spring I24 seats. The coil spring I24 seats against the legs I22 of the switch block shaft I2I to normally retain the switch block I25 out of contact with the terminals I26 and I21.

It wfll be noted that when the switch block I25 is out of contact with the switch terminals I26 and I21, the solenoid circuit is open and the solenoid II3 remains de-energized, so that the driving motor I will continue to rotate the main chain conveyor sprocket 82 and advance the worksupporting hangers B and B. When the cylindrical wall of cup 22 of the work-supporting hanger B or B strikes the contact roller I20, however, switch block I25 is pushed into contact with the contact points I26 and I21 so as to close the solenoid circuit, energizing the solenoid I I3 which operates to withdraw the companion clutch I01 out of meshing contact with the idler clutch I08, thus halting the advance of the main conveyor chain. When this occurs current will flow through the switch blocks I25 and into the branch wire I28 which is connected to the gap contact ring I3I of the time clock I30. When this occurs the contact hand I32.begins to swing counterclockwise about its shaft I33 around the contact ring I 3 I the hand I32 being connected to ground wire I35. When the time clock hand I 32 has made substantially a complete revolution, its end rides into the gap I3I between the ends of the contact ring I3I so as to break the circuit and de-energize the solenoid II3. Companion clutch I01 will then slide into engagement with the idler clutch I08 so as to cause the driving motor I00 to again rotate the main conveyor chain sprocket 82. When this occurs cup 22 of the work-supporting hanger B and B will move out of contact with the contact roller I20 which operates the switch block I25 so as to also break the circuit at this point.

In order to bring the time clock into proper starting position, the time clock is provided with a suitable coil spring I40 which mechanically carries the clock hand I32 over the gap between the ends of the arcuate contact ring I3I so that the contact hand I32 of the clock is again in contact with the contact ring I3I when the next worksupporting spindle .20 has advanced to the point where it will engage the contact roller I20. To prevent the clock spring I40 from rotating the clock hand I32 beyond the contact ring gap I3 I there is provided a locking device which prevents rotation of the hand I32 except when the contact block I25 is in electricalcontact with contact point I 26. It will be noted that the hand shaft I33 has fixed thereto a cam I34 which is engaged by a hook lever I 39 to prevent further counter-clockwise rotation of the hand I32. The hook lever I39 is moved out of contact with the cam I34 by means of a solenoid I36 connected to the hook lever I39 by solenoid shaft I38. Solenoid I36 has one of its termini connected to contact point I26 by lead wire I29 and its other terminus connected to ground wire I31. Thus it will be appreciated that when contact block I25 contacts terminal point I26 current will flow through solenoid Wire I29 and into the solenoid I36 which operates to pivot hook lever I39 and release the cam I34 so that current flowing into the time block through lead wire I28 will drive the hand I32 counter-clockwise until it again reaches the gap I3I in contact ring I3I Thus the coil spring I40 will rotate the hand I32 over the gap in ring I3I after the clock circuit has been broken. Upon breaking of the clock circuit the solenoid I36 will be deenergized, permitting the hook lever I39 to move into engagement with the shoulder I34 on the cam I34 and prevent the coil spring I40 from rotating the hand I32 beyond its proper contact starting position shown inFig. 8.

Since electrical time clocks are well-known, its construction has been only diagrammatically illustrated. The contact roller I20'and its associated contact block I25 and terminal contacts I26 and I26 encased in a suitable switch box, may be suitably suspended from track section C" directly above the initial blast stream a, with the contact roller I20 positioned in'the line of travel of cups 22 of the work-supporting hangers B. Thus when the cup 22 of the hanger strikes the contact roller I20, the workpiece 12 will be indexed directly in the blasting stream a to receive the full force of the abrasive blast. The abrasive throwing wheel which projects the blast stream a and the wheels which project further blast streams are so relatively and uniformly spaced that other hangers B and B will accurately index their suspended workpieces in each of the respective blast streams when a workpiece is indexed in blast stream a. This is made possible by reason of the uniform spacing of the hangers B all of which are connected by conveyor chain 10.

The indexing mechanism herein illustrated permits continuous operation of the main driving motor I 00 and thus eliminates power wastag in starting torque on the motor. This control device also insures positive and accurate indexing of the work-supporting hangers so that their workpieces are accurately suspended directly in all of the blasting streams. The contact block I25 and its associated contact roller I20 may be positioned directly above one of the blasting zones or it may be positioned considerably to one side of the blasting zone since all hangers B are uniformly spaced along the main conveyor chain 10,

All of the spindle-driving sprockets 36 and 36' are rotated during their residence in the blasting streams a and a by a continuously driven motor I45 which carries a drive pulley I46. A drive belt I41 is trained around motor pulley I46 and around a pulley I43 attached to the shaft I 49 of reduction gearing I50, as illustrated more particularly in Fig. 1. Reduction gearing I50 is provided with a driven sprocket I5I over which is trained a continuous drive chain I52 also trained around a sprocket I53 fixed to a stub shaft I54 adjacent the path of travel of the work-supporting hangers when moving through the blasting section 2 of the cabinet. The stub shaft I54 rotates in a bearing collar I55 suitably secured to the top wall I0 of the cabinet. Stub shaft I54 has fixed thereto a spinner chain sprocket I56 around which is trained one end of the continuous spinner chain 31 designed to mesh with spinner sprockets 36 and 36' attached to the spindles 33 of work-supporting hangers B and B, as previously explained. The other end of the continuous spinner chain 31 is trained around a sprocket I50 having a hub I53 which rotates on a stationary stub shaft I60 fixed to a socket I6I supported on the top wall I0 of the cabinet. The sprocket-engaging run of the spinner chain 31 moves in the direction indicated by the arrow in Fig. 4.

To insuregiositive driving engagement between spinner chain 31 and spinner sprockets 36 and 36', it is desirable to provide chain backing means directly above blasting streams a and a. I have provided a backing means for this purpose which is simple in construction and highly efiicient in operation. As illustrated more particularly in Figs. 1, 4 and 5, a chain backing pedestal I62 is positioned directly above each blasting stream, rests upon the top wall I of the cabinet and is positioned between the inner and outer runs of spinner chain 31. Each backing pedestal comprises a stub shaft I63 whose lower end is fixed to a base I 64 rigidly supported on the top wall I0 of the cabinet. A heavy chain contacting disc I65 provided with a hub portion I66 is free to idle on stub shaft I63 and is positioned between the inner and outer runs of spinner chain 31 with its periphery positioned to bulge the sprocket-engaging run of the chain, as illustrated more particularly in Fig. l. The contact disc I65 may be removably mounted on the stub shaft I63 by means of a collar I61 removably secured to the upper end of stub shaft I63. by a removable key or set screw I68.

To reduce friction and permit the spinner chain 31 to smoothly roll over the peripheries of the contact discs I65, the spinner chain 31 is provided with roller sleeves I10 which are free to roll on the pins "I which connect the paired outer links I12 to the paired inner links I13 of the chain. The chain rollers I10 roll over or with the peripheries of the contact discs I65 substantially without friction and yet serve to bulge the inner run of the spinner chain 31 so that it positively engages the spinner sprockets 36 and 36'. It will be noted that each chain pedestal I62 is positioned directly above each blasting stream a and a so that the hanger sprockets 36 and 36' will be positively engaged and rotated by the spinner chain. The contact discs I65 also serve to maintain the spinner chain 31 taut.

Means are provided to further insure positive engagement between the spinner chain 31 and the spindle sprockets 36 and 36' and to prevent the spindles 33 from swaying or swinging while traveling through the blasting streams. By referring more particularly to Figs. 1, 4, 5 and 6, it will be noted that each work-supporting spindle 33 carries a contact disc I15 having a hub portion I16 which is secured to the spindle 33 and rotates therewith. The periphery of each contact disc I15 is arranged to roll in contact with a series of free rollers I11 which extend along the path of travel of the hangers as they move through the blasting zone. Each roller I11 is free to rotate on a pin I18 fixed at each end to the legs of a U- shaped bar I19 which extends along the path of travel of the hangers. The U-shaped bar I19 may be secured to a plurality of spaced brackets I80 having their foot portions I8I secured to the top wall of the cabinet, as more particularly illustrated in Figs. 1 and 5, The U-shaped rollersupporting bar I19 carrying the closely spaced contact rollers I11 may extend the full distance between and slightly beyond the spaced abrasive streams a and a so that each hanger spindle 33 is prevented from swinging on the track section C" as it advances through the blasting zone.

It will also be noted that the chain-engaging peripheries of the contact discs I65 bulge the driving run of the spinner chain 31 to the point where the spinner sprockets 36 and 36' will not interfere with the rotative movement of the chainsupporting sprockets I56 and I58. The spinner sprockets 36 and 36 will engage the driving run of the spinner chain 31 at a point somewhere between the idling sprocket I58 and the adjacent pedestal I62, and the spinner sprockets-35 and 36 will disengage themselves from the driving run of the spinner chain 31 somewhere between the other pedestal I62 and the driving sprocket I56.

Thus the spinner sprockets 36 and 36' freely move into and out of engagement with the spinner driving chain 31 to rotate all of the work-supporting spindles 33 during their advance along the blasting section 2 of the cabinet.

Abrasive cycling mechanism G is provided for transporting abrasive from the abrasive receiving hopper I3 contained in the floor pit F to the abrasive throwing wheels W. As illustrated more particularly in Figs. 1, 2 and 3, the abrasive ,cycling mechanism may comprise an enclosed elevator housing I which extends through the rear portion of the blasting section 2 of the cabinet and into the fioor pit F. The elevating housing I90 contains a continuous elevator belt I9I carrying abrasive buckets I92. The lower end of the elevator belt I9I is trained around a suitable pulley I93 in the boot of the elevator housing I90 into which the reduced lower end of the abrasive hopper I3 extends. The upper end of the elevator belt I9I is trained around a belt pulley I94 within the top end of the elevator housing I90.

A spillway chute I95 is provided at the upper end of the elevator housing I90, into which the abrasive cycling buckets I92 dump their loads of abrasive. The spillway chute I95 empties the abrasive into an abrasive receiving tube or conduit I96, whence the abrasive moves into an overhead abrasive receiving tank I 91 suitably supported from the top wall In of the cabinet. The abrasive receiving tank I91 is provided with a plurality of abrasive receiving hoppers I99 in the bottom thereof which lead to abrasive discharge spouts I99. The lower end of each abrasive discharge spout I99 is provided with a control valve 200 to control the volume of abrasive discharge from the spout I99. The abrasive is conducted from each of the spouts I99 into the funnel 20I of an abrasive feed pipe 202 of suitable lengthwhich conducts the abrasive to the funnel portion of the feed spout associated with each wheel.

The abrasive cycling mechanism is driven by a motor 203 supported upon a suitable platform 204 fixed to the elevator housing I90. The motor 203 is connected to a speed reducer 205 whose drive shaft 206 carries a sprocket wheel 201 over which drive chain 208 is trained. The bucket belt pulley I94 is fixed to a shaft 209 which carries a sprocket 2I0 over which drive chain 208 is trained and provides a driving connection between the motor 203 and the elevator belt I9I.

To convey the abrasive through the abrasive conduit I96, a screw or flight conveyor 2I I is contained within the tube I96, the flight conveyor 2 being fixed to a suitable shaft 2I2 one end of which is journaled in a bearing supported by the elevator housing I90 and the other end of which is journaled in a bearing fixed to the side wall of the abrasive-receiving tank 691. The shaft 2I2 of the flight conveyor 2 is driven by means of a bevel gear 2I3 fixed to the end thereof, bevel gear 2I3 meshing with bevel gear 2 fixed to a shaft 2 I 5 which may extend through and be journaled in bearings mounted on the side walls of the elevator housing I90. Shaft 2I5 has a sprocket 2I6 fixed thereto over which is trained a drive chain 2I1 which is also trained over a sprocket 2| 8 fixed to the shaft 206 of the gear reducer 205. Thus, the elevator motor 203 also operates to drive the shaft 2I2 of the flight conveyor.

. with. The spiral agitator 220 rolls the abrasive material within the tubular screen 2I9 so as to cause the usable abrasive to escape through the tubular screen 2I9 and fall into the abrasivereceiving tank I91. The stationary screen 2I9 has an openingv 22I in its end,v through which clinkers and other coarse material removed from the castings during the blasting operation may discharge into a receiver 222 which leads into a gravity discharge pipe 223. A dust collector (not shown) may be connected to a dust discharge port 224 of the abrasive-receiving tank I91. The tank I91 may also contain mechanism (not shown) for removing dust, broken unusable abrasive, and other undesirable material from the abrasive cycled into the tank I91, so that only clean and usable abrasive is supplied to the abrasive blasting wheels W. One of the side 'walls 1 oi the blasting section 2 of the cabinet may be provided with an inspection door 225 so that the operating mechanism contained within the cabinet may be conveniently inspected and repaired.

The front wall 5 of the entrance vestibule I may be provided with an entrance opening 230 and the front wall 6 of the exit, vestibule 3 may be provided with an exit opening 23| through which the suspended workpieces may enter the entrance vestibule and leave the exit vestibule.

Each of the door openings 230 and 23| is nor-' mally closed by paireddoors 233 which may be made of either flexible rubber or steel. Each of the hangers is provided with a cone-shaped member 234 which is fixed to the rotatable spindle 33 of each of the hangers B and B. Each cone-shaped shield 234 is of such diameter and so arranged that the peripheral portion 235 thereof will engage the paired doors 233 during advance movement of the hangers to swing the doors open so that the workpieces 10 need 101; strike the doors.

The cone-shaped shields 234 have the?! reduced ends 236 arranged to extend into the slot 35 in the top wall I of the cabinet, as illustrated.

more particularly in Figs. and 6, so as to partially close the slot and prevent abrasive from escaping from the cabinet and damaging the mechanism mounted on the top wall of the cabinet. To further prevent the escape of abrasive through the slot 35 in the top wall of the cabinet, a pair of downwardly inclined baflie plates 23! are provided whose upper ends are secured to the framing l5 which extends along and on each side of the slot 35. A flexible rubber baiile 238 is secured to each of the downwardly inclined baflie plates 231 as by means of a clamping plate 239 and bolt 240. A downwardly inclined end portion 2. of each flexible baflle 238 is free to flex around the hanger spindles 33 as they move therebetween.

Abrasive sealing means is also provided above the path of travel of the cone-shaped shields 234, as illustrated more particularly in Fig. 5. This further sealing means comprises a pair of lower flexible 'rubber flaps 244 and a pair of upper flexible rubber flaps 245. Each of the lower flaps 244 rests on a bar 246 seated on the top wall I0 of the cabinet closely adjacent to the slot 35. A U-shaped spacing member 241 has the lower leg 248 thereof resting on one of the bars 240 with the lower flaps 244 clamped therebetween. The upper flaps 245 rest on the upper leg 243 or the U-shaped member 241 and is held in place by a clamping bar or member 250 held in place by screws 25I By this novel sealing arrangement a triple seal is provided along the path or travel of the spinner spindles 33 which positively prevents any escape of abrasive from within the cabinet through the slot 35 in the top wall of the cabinet. The flexible flaps 238 provide an initial seal within the cabinet. The cone-shaped shields 234'flxed to each or the spinner spindles 33 provide a further and secondary seal. Finally, the paired flexible flaps 244 and 245 provide a tertiary seal which absolutely prevents any dust or other particles that may have escaped through the flexible baflle 238 and the cone-shaped shields 234 from escaping into the atmosphere.

My improved blasting apparatus permits convenient loading of the workpieces p at the loading station adjacent the loading section 0' of the track 0. The loading can be easily and conveniently done during the interval in which the hangers remain stationary. The hangers B with their suspended workpieces p are successively advanced into the entrance vestibule I and thence proceed into the main blasting section 2 or the cabinet. Each hanger halts directly in each of the successive blasting streams a and a and resides in each of these blasting streams for a period which is determined by the setting of the time clock I30 which is associated with the conveyor-advancing mechanism D.

During the progress'of the hangers and suspended workpieces through the blasting section of the cabinet, they are rotated by the spinner drive chain 31 with the spindles 33 of alternate hangers B rotating in one direction and the spindles 33 of intermediate hangers B rotating in the opposite direction, so that substantially all of the projected abrasive performs useful work in cleaning the workpiece surfaces. The walls I and 8 of the blasting section of the cabinet are so spaced and arranged that any abrasive fired from the wheels W that does not strike the workpieces loses substantially all of its abrading velocity before it strikes the cabinet walls 'I and 8.

The spinner-rotating mechanism is so constructed and arranged as to smoothly engage the spinner sprockets 36 and 36' substantially with out shock or strain on the parts. The hangers B and B are prevented from swinging movement during their travel through the blasting section by the contact discs I65 of pedestals I 62 and guide rollers Ill. The workpiece-supporting spindles 33 may be rotated at any desired speed of rotation by a proper adjustment of the reduction gearing I50.

The conveyor advancing mechanism is so arranged and constructed that the workpieces are quickly advanced from one blasting stage to the next blasting stage with a minimum loss of time but yet permit the workpieces to dwell in each blasting stream for any desired cleaning period, which may be regulated and controlled to a fraction of a second by the ,time clock I30. Since the spinner speed reducer I50 is completely independent of the hanger speed reducer 11, each may be adjusted and controlled as desired independently of the other. By equally spacing the hangers B and B along the conveyor chain 31 positive registry of each of the workpieces in the successive blasting streams is'assured. Any desired number of abrasive throwing wheels W may be provided, arranged at any desired elevation for rotation clockwise or counterclockwise. The workpieces emerging from the exit vestibule 3 of the cabinet may be conveyed to any desired location in the shop before being removed from the hangers adjacent the unloading section of track C.

While certain novel features of the invention have been disclosed and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. In blast cleaning apparatus including a blasting station, a work-supporting carrier,

'means for transporting said carrier along a predetermined path, said work-supporting carrier including a carriage portion, a work-supporting spindle, means rotatably connecting said spindle to said carriage, and a sprocket operatively connected to said spindle, a continuous drive chain having an outer run and an inner run positioned along the path of travel of said spindle sprocket, means for driving said drive chain to rotate said work-supporting spindle during its advance movement, and means including a free- 1y rotating contact disc positioned between the inner and outer runs of said drive chain substantiallyin line with the blasting station to receive side thrust exerted on the carrier at the blasting station, said disc being arranged to bulge the inner sprocket engaging run of said chain to facilitate engagement of said spindle sprocket with said chain.

2. In blast cleaning apparatus including a pair or blasting stations, a work-supporting carrier, means for transporting said carrier along a predetermined path, said work-supporting carrier including a carriage portion, a work-supporting spindle, means rotatably connecting said spindle to said carriage, and a sprocket operatively connected to said spindle, a continuous drive chain having an outer run and an'inner run positioned along the path of travel of said spindle sprocket, means for driving said drive chain to rotate said work-supporting spindle during its advance movement including, a chain supporting sprocket at each end of said drive chain, reduction gearing operatively connected to one of said chain sprockets, a driving motor operatively connected to said reduction gearing, and means including a pair of freely rotating contact discs positioned between the inner and outer runs of said chains substantially in line with said blasting stations to receive side thrust exerted on the carrier at the blasting stations, said discs having their peripheries positioned to bulge the inner sprocket engaging run of said chain to facilitate engagement of said spindle sprocket with said chain.

3. In blast cleaning apparatus, a*work-supporting carrier, means for transporting said carrier along a predetermined path, said work-supporting carrier including, a carriage portion, a work-supporting spindle, means rotatably connecting said spindle to said can iage, and a sprocket operatively connected to said spindle, a drive chain having a run thereof positioned along the engaging run of said drive chain, and a plurality of rollers rotatably supported .by said guid member against which the periphery 01! said contact disc may roll during advance movement of the sprocket operatively connected to said spindle, a 1

continuous drive chain having an outer run and an inner run positioned along the path of travel of said sprocket, means for driving said drive chain to rotate the work-supporting spindle during its advance movement, means including a freely rotating contact disc positioned between the inner and outer runs of said drive chain and having its periphery positioned to bulge the inner sprocket engaging run of said chain to facilitate engagement of said spindle sprocket with said chain, a contact disc fixed to said spindle, a guide member positioned along the path of travel of said spinner contact disc opposite the sprocket enga ing run of said drive chain, and a plurality of rollers rotatably supported by said guide member against which the periphery of said spinner contact disc may roll during advance movement of the hanger to retain the sprocket in driving engagement with the sprocket engaging run of said drive chain.

5. In blast cleaning apparatus, a track, a work supporting hanger movable along said track, said hanger including, a roller carriage supported by and movable along said track having a downwardly extending leg portion, a tubular receiver fixed to said leg, 8. bearing sleeve fixed to said tubular receiver, a thrust bearing positioned within and supported by said sleeve, a collar member having one end thereof rotatably mounted in said sleeve, a hanger spindle supported in said thrust bearing and connected to said collar member, a work-supporting spindle fixed to said collar member, and a sprocket fixed to said work-supporting spindle, a drive chain having a run thereof positioned along the path of travel of said sprocket, a conveyor chain connected to said leg portion, means for driving said conveyor chain to advance the carriage along said track, and means for driving said sprocket chain to rotate said work supporting spindle during its advance movement.

6. In blast cleaning apparatus, a track, a worksupporting hanger movable along said track, said hanger including, a carriage supported by said track, a tubular sleeve fixed to said carriage, a thrust bearing positioned within said sleeve, a work-supporting spindle rotatably supported from said thrust bearing, a sprocket, and mechanism operatively connecting said sprocket to said spindle whereby said spindle will be rotated in a direction opposite to the direction of rotation of said sprocket, a drive chain having a run thereof positioned along the path of travel of said sprocket, and means for driving said drive chain to rotate said work-supporting spindle during its advance movement.

7. In blast cleaning apparatus, a track, a carriage supported by and movable along said track, a tubular sleeve fixed to said carriage, a thrust bearing positioned within said sleeve, a worksupporting spindle rotatably supported by said thrust bearing, a sprocket mounted on said spindle, a drive chain having a run thereof positioned along the path of travel of said sprocket, means for driving said drive chain to rotate said sprocket during its advance movement, and means for rotating said work-supporting spindle in a direction opposite to thedirectlon of rotation of said sprocket.

8. In blast cleaning apparatus, a track, a carriage supported by and movable along said track, a tubular sleeve fixed to said carriage, a thrust bearing positioned within said sleeve, a worksupporting spindle rotatably supported by said thrust bearing, a sprocket mounted on said spindle, a drive chain having a run thereof positioned along the path of travel of said sprocket, means for driving said drive chain to rotate said sprocket during its advance movement, and means associated with said sprocket and work-supporting spindle for rotating said spindle in a direction opposite to the direction of rotation of said sprocket, said means including a sleeve fixed to said sprocket and rotatable on said spindle, a driving gear fixed to said sleeve, a transfer gear meshing with said driving gear, and a gear fixed to said spindle in meshing engagement with said transfer gear.

9. In blast cleaning apparatus, a track, a roller carriage supported by and movable along said track, a tubular sleeve fixed to said carriage, a thrust bearing positioned within said sleeve, a work-supporting spindle rotatably supported by said thrust bearing, a gear box fixed to said sleeve and enclosing a portion of said work-supporting spindle, a sprocket sleeve rotatably mounted on said spindle and having the end portion thereof extending into said gear box, a sprocket fixed to said sleeve exterior to said gear box, a driving gear within said gear box fixed to said sleeve, a transfer gear meshing with said driving gear rotatably supported within said gear box, a gear fixed to said work-supporting spindle within said gear box meshing with said transfer gear, and means for rotating said sprocket to rotate said work-supporting spindle in a direction opposite to the direction of rotation of said sprocket.

10. In blast cleaning apparatus, a track, a roller carriage supported by and movable along said track, a tubular sleeve fixed to said carriage, a thrust bearing positioned within said sleeve, a carriage spindle rotatably supported by said thrust bearing, a work-supporting spindle fixed to said carriage spindle, a collar member fixed to said sleeve, a gearbox fixed to said collar member and enclosing the upper end portion of said work-supporting spindle, a sprocket sleeve rotatably mounted on said spindle and having a portion thereof extending into said gear box, a sprocket fixed to said sprocket sleeve exterior to said gear box, means for rotating said sprocket, and a device for rotating said work-supporting spindle in a direction opposite to the direction of rotation of said sprocket including a driving gear within said gear box fixed to said sprocket sleeve, a transfer gear meshing with said driving gear rotatably supported within said gear box, and a gear fixed to said work-supporting spindle within said gear box meshing with said transfer gear.

11. In blast cleaning apparatus, a stationary track, alternate and intermediate work-supporting hangers movable along said track, a conveyor chain for advancing the workpieces suspended from said hangers through a blasting zone, means for driving said conveyor chain to advance the workpieces suspended from said hangers through said blasting zone, and mechanism for rotating the spindles of alternate hangers in one direction during their travel through the blasting zone and the spindles of intermediate hangers in the opposite direction during their travel through the blasting zone, said spindle rotating mechanism including a single spinner chain, means for driving said spinner chain in one direction only, a spinner sprocket directly fixed to each of the work-supporting spindles of alternate hangers and a spinner sprocket associated with each of th work-supporting spindles of intermediate hangers, the sprockets of said alternate hangers and the sprockets of said intermediate hangers being positioned to be driven in the same direction by said single drive chain, and means for operatively connecting the sprocket and spindle of each intermediate hanger so that its spindle will be rotated in a direction opposite to the direction of rotation of its associated sprocket.

12. In blasting cleaning apparatus, a stationary track, alternate and intermediate work-supporting hangers movable along said track, a conveyor chain for advancing the workpieces suspended from said hangers through a blasting zone, a continuously operated driving motor, cooperating mechanical and electrical mechanism for detachably connecting and disconnecting said motor to said conveyor chain to periodically advance the workpieces suspended from said hangers into, through and out of said blasting zone, to index the workpieces in said blasting zone and to selectively control the period of exposure of the workpieces in said blasting zone, and mechanism for rotating the spindles of alternate hangers in one direction during their travel through the blasting zone and the spindles of intermediate hangers in the opposite direction during their travel through the blasting zone.

13. In blast cleaning apparatus, a stationary track, a work-supporting hanger movable along said track, a cfinveyor chain fixed to said hanger, a continuously operated driving motor for periodically driving said conveyor chain to advance said hanger along said track, an abrasive projector for projecting a stream of abrasive into a predetermined blasting zone positioned along the path of travel of the work supported on said hanger, and mechanism for controlling the period of exposure of the work supported on said hanger in said blasting zone, said mechanism including a tim clock, a switch device having an element positioned to be engaged by said hanger during its advance to operate said switch, a clutch operatively connected to said conveyor chain and 7 adapted to be moved into and out of driving relation with said motor, an electrical device operatively connected to said clutch to throw said conveyor chain into and out of driven relation with said motor, and an electric circuit electrically connecting said conveyor drivingmotor, electrical clutch operating device, contact switch and time clock whereby said electrical clutch operating device is retained out of driven relation with said motor during a predetermined time period established by the setting of said time clock.

14. In blast cleaning apparatus, a stationary track, a plurality of work-supporting hangers movable along said track, a conveyor chain fixed to and uniformly spacing said hangers along said track, a continuously operated driving motor for periodically driving said conveyor chain to advance said hangers along said track, an abrasive projector for projecting a stream of abrasive into a predetermined blasting zone positioned along the path 01' travel of the workpieces supported on said hangers, and mechanism for controlling the period of exposure 01 the workpieces and indexing the workpieces supported on said hangers in said blasting zone, said mechanism including a time clock, a switch'device having an element positioned to', be engaged by successive hangers during their. advance movement to close said switch when contacted by said hanger, a clutch operatively connected to said conveyor chain and adapted to be moved into and out of driven relation with said motor, an electrical device operatively connected to said clutch to throw said conveyor chain into and out of driven relation with said motor, and an electric circuit electrically connecting said conveyor driving motor, electrical clutch operating device, contact switch and time clock whereby said electrical clutch operating device is retained out of driven relation with said motor during a predetermined time period established by the setting of said time ock. c1 15. In blast cleaning apparatus, a stationary track, a work-supporting hanger movable along said track, a continuous conveyor chain flxed to said hanger, a continuously operated driving motor, a driving sprocket having a driving connection with said conveyor chain, means including a clutch device for operatively conecting said motor to said sprocket, said clutch device having a clutch part driven by said motor and a movable clutch part connected to said sprocket, an electrically operated device operative to move said movable clutch part into and out of driving engagement with said motor driven idling clutch part, a contact element positioned in the path of travel of said hanger, a switch associated with and adapted to be opened and closed by said contact element, an electrically driven time clock, and an electric circuit electrically comected to said motor, clutch part operating device, contact switch, and time clock whereby said time clock operates to control the time period in which said movable clutch part is retained out of operative engagement with said motor driven clutch part.

16. In blast cleaning apparatus, a stationary track, a plurality of work-supporting hangers movable along said track, a continuous conveyor chain fixed to and uniformly spacing said hangers, a continuously operated driving motor, a driving sprocket having a driving connection with said conveyor chain, reduction gearing having a driving connection with said sprocket, a drive shaft associated with said reduction gearing, a clutch device having a clutch part normally idling on said shaft and a movable clutch part normally fixed to rotate with said shaft, driving means connecting said motor to said idling clutch part, an electrically operated device operative to move said movable clutch part into and out of driving engagement with said motor driven idling clutch part, a contact element positioned in the path of travel of said hangers, a switch associated with and adapted to be opened and closed by said contact element, an electrically driven time clock, and an electrical circuit electrically connected to said motor, clutch part operating device, contact switch and time clock whereby said time clock operates to control the time period in which said movable clutch part is retained out of operative engagement with said motor driven clutch part.

1'7. In blast cleaning apparatus, a blast cabinet, a plurality of work-supporting carriers, a work-supporting spindle suspended from each of said carriers and extending througha slot in the top wall of said cabinet, means for transporting said carriers and associated spindles along a predetermined path defined by said slot, abrasive projectors projecting a plurality oi stream 01' abrasive into said cabinet along the path of travel of the work-pieces supported by said spindles, and sealing means for preventing escape of abrasive through said slot, said sealing means including a pair of spaced trough forming baifle plates projecting into the cabinet from the top wall thereof with said slot positioned between said plates, a pair of flexible baifle members fixed to the lower ends of said baflie plates and forming with said baiiie plates a substantially closed trough but adapted to be flexed by the advance movement of said spindles, a pair of flexible sealing members exterior to said cabinet arranged to substantially seal said slot but adapted to be flexed by the advance movement of said spindles, and a cone-shaped shield fixed to each of said spindles and movable between said paired flexible baiile members and within said trough.

18. In blast cleaning apparatus, a stationary track, work supporting hangers movable along said track, a conveyor chain connecting said hangers, means including a clutch for advancing said conveyor chain to advance workpieces suspended from said hanger; through a blasting zone, and cooperating electrical and mechanical mechanism for indexing the workpieces in said blasting zone and for selectively controlling the period of exposure of the workpieces in said blasting zone, said mechanism including contact means operable by said hangers and time controlled switching means actuated by said contact means for operating said clutch during a predetermined length of time.

19. In blast cleaning apparatus, a track, a work supporting carriage movable along said track, a work supporting spindle rotatably supported from said carriage, a sprocket rotatably mounted on said spindle, a drive chain having a run thereof positioned along the path of travel of said sprocket, means for driving said drive chain to rotate said sprocket, and means for rotating said work supporting spindle in a direction opposite to the direction of rotation of said sprocket.

DAVID C. TURNBULL.

CERTIFICATE OF CORREC'II ON.

Patent No. 2,5M u75. March 11;, 191i.

DAVID c. TURNBULL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring tionas follows: Page h, first column, line 67, for "from" read front--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of May, A. D. 191m.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

